Although the art of designing and building safes is quite old, it seems that each new refinement which is intended to thwart unauthorized opening of a safe merely invites the application of new method and ingenuity to overcome the newest designs. Modern safes generally employ a plurality of locking bolts which extend from the safe door into apertures in the opening in the safe. The locking bolts are selectively withdrawn by rotation of a cam plate by a spindle which extends through the safe door to the exterior thereof. The spindle has a numbered dial on the exterior end thereof, and a plurality of combination wheels or tumblers on the interior end thereof. When all of the tumblers are properly aligned, a bail or fence which extends from the cam plate engages the aligned slot in the tumblers so that rotation of the dial and spindle will rotate the cam plate and withdraw the locking bolts to open the safe door.
Although safe doors and locking mechanisms appear formidable, ingenious burglars have devised simple methods for breaching the seemingly impregnable modern safe construction. For example, a burglar may use a hammer to knock the combination dial off of the exterior end of the spindle, and then use the hammer to drive the spindle axially inwardly to effect release of the locking mechanism. Another common method involves drilling into the safe wall adjacent to the door in the general area of the aperture which receives a locking bolt. The locking bolt may then be punched inwardly to thereby free the door and burglarize the contents of the safe. These methods may be countered by the use of massive construction of the safe parts, but this approach is extremely costly. In small safes for home or office use, where cost is an important consideration, the thickness and strength of the materials used tend to invite the burglarizing methods mentioned above.